An air conditioning and refrigeration system consists of a relatively simple group of components that, collectively, are capable of transferring heat, through an intermediate fluid substance known as a refrigerant, from a relatively cool environment to a relatively warm environment. However, when the basic thermodynamics of air conditioning or refrigeration is applied to reversing this heat flow from inside-to-outside to outside-to-inside' without a reversible compressor, a heat pump is required, increasing the complexity of the air conditioner with additional system plumbing, solenoid valving, controls, etc.
The basic capability of an air conditioning (cooling) system that is also able to supply heating (a heat pump), lies within the compressor. Conventional compressors are not flow-reversible devices. In a system capable of cooling only, for example, the hot discharge refrigerant gas is routed directly to the heat exchanger residing in the relatively warm outside environment where relatively high-energy (high enthalpy) hot discharge refrigerant gas is condensed isothermally to a liquid due to the heat being transferred to the outside environment by a heat exchanger, referred to as a condenser.
The relatively warm, condensed (liquid phase), high pressure refrigerant then flows through a small orifice, known as an expansion valve, and into another heat exchanger (known as the evaporator) that is located within the cooled space, and is operating at low pressure because of the “suction” provided by the inlet flow into the intake of the compressor. A physical phenomenon, known as the Joule-Thompson effect, takes place as the liquid refrigerant that passes through the expansion valve becomes very cool due to the significant pressure differential it experiences as it flows across the orifice.
Because of a drop in the pressure the refrigerant experiences as it flows through the expansion valve, a portion of the liquefied (condensed) refrigerant leaving the expansion valve flashes into a vapor phase. This rapid drop in refrigerant pressure results in the flashed vapor and the remaining liquid refrigerant to become relatively cold. The remaining cold, low-pressure refrigerant flows through the evaporator where it absorbs heat from the air in the cooled space it is located in, causing the refrigerant to evaporate into its gaseous phase. The refrigerant then reenters the inlet of the compressor where the cycle repeats.
Conventional compression devices and valving systems are unable to exchange the inlet port for the outlet port by reversing the machine's rotational direction. In other words, conventional compression devices are not flow-reversible. In certain applications, such as air conditioning and heat pump systems, true compressor reversibility would be of exceptional value.
Since conventional compressors are not flow-reversible, when it is necessary to transfer heat from the outside environment to the inside to provide heating, additional hardware is required. The hot gas discharging from the compressor is re-routed from flowing to the outside heat exchanger to the inside heat exchanger through the use of additional plumbing and electrical solenoid valves, as described above. Subsequently, heat transferred to the inside heated space results in the condensation of the hot refrigerant gas to liquid form.
This relatively warm liquid refrigerant is required to be re-routed through additional plumbing, valving and controls to the outside environment heat exchanger after it passes through an expansion valve where the Joule-Thompson effect re-occurs causing the refrigerant to be colder than the outside environment. Due to the temperature difference, heat is absorbed through the heat exchanger that is now behaving as an evaporator.
As the environmental heat residing in the cool or cold outside is being transferred to the outside heat exchanger, the refrigerant evaporates as it absorbs the heat and returns to the gaseous phase. Having converted to a gas as a result of absorbing heat, the refrigerant re-enters the compressor inlet through additional plumbing, valving and controls; again, bringing the system to cyclic repetition.
On the other hand, if the refrigerant compressor had the capability to reverse its flow, the air conditioner would become a heat pump without requiring the additional plumbing, valving, controls, etc., required by conventional heat pumps. Since conventional compression devices and valving systems are unable to exchange the inlet port for the outlet port by reversing the rotational direction of the machine, they are not flow-reversible. In certain applications, such as air conditioning and heat pump systems, true compressor reversibility would be of exceptional value. For these reasons, a need exists for a reversible valving system for use in compressor devices.